SA516 Gr.70 PWHT

By Lawrence (*****)

Date 01-20-2005 20:18

This may or may not apply.

Note A516 Rather than SA516

Bethel Steel has data for A516 http://www.bethsteel.com/customers/pdfs/specguide.pdf

Among other things it notes (pgs. 12-14) That post weld heat treat may degrade the heat affected zone strength and toughness and suggests pre-testing procedures.

By G.S.Crisi (****)

Date 01-20-2005 20:38

A 516 is an ASTM designation for low carbon steel plate suitable for low temperature service. SA 516 is an ASME designation, described on ASME Boiler Code Section II.
In the majority of cases both materials are identical but sometimes there are slight differences. It's always advisable to take a look at the ASME Boiler Code Section II and check whether or not the materials are the same.
In most cases A 516 (or SA 516) is used to make pressure vessels. In these cases the requirements of ASME Boiler Code Section VIII, including those for PWHT, apply.
However, sometimes I've seen A 516 used to make large diameter piping (i.e., above 24 inches in diameter) for refineries and chemical plants. In these cases, ASME/ANSI B 31.3 Code for Pressure Piping is applicable.
If the steel is used for a different application, it's necessary to see whether this application is ruled by some Code or standard. If it is, then that Code of standard must be followed.
As a preliminary opinion, i.e., without having read ASME VIII and B 31.3, I'd say that Dancer's client requirement is reasonable.
Giovanni S. Crisi
Sao Paulo - Brazil

By jon20013 (*****)

Date 01-20-2005 21:12

From my experience with ASME welds, I have found in most cases it is dependant on thickness of the weld joint. Which constructing code applies, Dancer? I believe in many instances even ASME VIII may exempt PWHT for joints less than 1/2" thick if the material is .30 carbon or less and if preheated to 200F.

By Dancer Date 02-01-2005 17:06

Hello Lawrence,
Thank you for your input.
Further to this issue, do you know what criteria determines the necessity for PWHT with SA515 Gr70 material?

By jon20013 (*****)

Date 02-01-2005 17:45

see above.

By Dancer Date 02-01-2005 18:22

Hi Jon20013
Do you happen to know which part of Section VIII covers this issue?

By Skiddy

Date 02-01-2005 18:56

Section UCS-56

By jon20013 (*****)

Date 02-01-2005 19:27

Yes, in particular, read Note 3 to Table UCS-56 which provides any allowable exemptions from PWHT. As I said before, it depends largely on the material thickness and joint design as to whether an exemption may be applied, or not. Sa-516, Grade 70 is a P-1, Group 2 material so if your material is preheated to 200F you MAY be exempted from PWHT. How thick is your material, and do you have any full penetration welds?

By jon20013 (*****)

Date 02-01-2005 21:30

Dancer, we seem to have all gotten sidetracked from your original question (except for Professor Crisi) so, in my own opinion, PWHT need not be on your PQR UNLESS you are using the WPS in applications which require PWHT. If you do not intend to use the WPS in PWHT applications a simple N/A addresses the essential variable. In the long run, what I have done with my company's WPS is run one coupon with and one coupon without PWHT so they can be combined into a single WPS with, or without PWHT.

By Dancer Date 02-08-2005 14:37

Hello All,
Thank you for your input.
The criteria I have determined for PWHT of SA516 Gr.70 material is that it is essential for welds greater then 1 1/2" (nominal thickkness) or 1/2" (nominal) for lethal service. There are other dependants and exceptions identified in UCS-56 which references UW-40 for the definition of 'nominal weld thickness'

Thanks again.